ANATOMY.docx

ANATOMY Anterior talofibular ligament most likely to be sprained (next to lateral malleolus) Arterial supply of the leg: Popliteal artery (continuation of femoral artery) divides into Anterior tibial & Posterior tibial (pulse post. to medial malleolus) Fibular artery arises from Posterior tibial...

ANATOMY Anterior talofibular ligament most likely to be sprained (next to lateral malleolus) Arterial supply of the leg: Popliteal artery (continuation of femoral artery) divides into Anterior tibial & Posterior tibial (pulse post. to medial malleolus) Fibular artery arises from Posterior tibial artery to supply posterior + lateral compartments Medial and lateral plantar arteries + deep plantar arch supply sole of foot In the vertebra, - nucleus pulposus surrounded by annulus fibrosus. Prolapse of the nucleus pulposus usually happens posterolaterally. In S1 impingement: Sciatic N. can be involved (L4 - S3) → gives rise to Tibial N (L4 - S3) and CPN (L4 - S2) In S1 / S2 impingement there is loss of hip lateral rotation + abduction ; loss of ankle plantarflexion + eversion ; toe dorsi + plantarflexion and diminished ankle jerk reflex Cauda Equina syndrome: Compression of spinal N. after inferior end of spinal cord (conus), causing red flag symptoms like saddle anaesthesia, diminished anal tone and later urinary / faecal incontinence Brachial Plexus Provides motor innervation to arm and shoulder muscles (except trapezius which is supplied by spinal accessory nerve) and sensory innervation to whole arm (except medial part which is supplied by intercostobrachial nerve) Roots: From anterior rami of spinal nerves C5 - T1 Trunks: Located in the neck Upper (C5, C6) Middle (C7) Lower trunk (C8) Divisions: Enters axillary fossa Anterior division supply anterior flexor compartment Posterior division supplies posterior extensor compartment Cords: Located in the axilla Lateral cord: anterior division of upper and medial trunks Musculocutaneous N., some of Median N. Medial cord: anterior division of lower trunk Ulnar N. Median N. formed from medial and lateral cord Posterior cord: posterior division of upper, medial and lower trunks) Radial N., Axillary N. Pathology: Erb’s palsy: C5 - C7 Klumpke’s palsy: C8 - T1 Rotator Cuff Muscles - Supraspinatus, Infraspinatus, Subscapularis, Teres Minor Cubital Fossa Contains Radial N., Brachial Artery, Median N., Bicipital Tendon Borders: Superior: Line joining medial and lateral epicondyle Medial: Pronator Teres Lateral: Brachioradialis Floor: Supinator Roof: Antebrachial fascia Pulleys of the Finger A1 pulley most affected in trigger finger (ring finger / thumb) Femoral Triangle Opening is Femoral Ring Borders: Superior: Inguinal Ligament Medial: Medial border of adductor longus Lateral: Medial border of the Sartorius Floor: Adductor Longus, Iiliopsoas, Pectineus Roof: Fascia lata Contains (L to M): Nerve, Artery, Vein, (Femoral Canal), Lymphatic vessels Femoral Canal within the femoral triangle contains fatty tissue and deep LN glands of cloquet Femoral sheath encircles Femoral Artery, Vein and Lymphatics (NOT NERVE!) Answers from Quiz: Neuroanatomy - Overview of the Nervous System CNS: 12 pairs of Cranial Nerves and 31 pairs of Spinal Nerves Primary Vesicles @ 4 weeks Secondary Vesicles @ 6 - 8 weeks Mature Brain Forebrain (Prosencephalon) Telencephalon Cerebral Hemispheres Diencephalon Thalamus, Hypothalamus Midbrain (Mesencephalon) Mesencephalon Midbrain Hindbrain (Rhombencephalon) Metencephalon Pons, Cerebellum Myelencephalon Medulla Cells of the NS: Neurons (mostly multipolar) Glial cells (most numerous cell type - 4 types) Astrocytes Star shaped with many processes ; maintain BBB = environmental homeostasis Oligodendrocytes Produce Myelin in CNS (Schwann cells in PNS) Microglia Macrophages of the CNS - immune monitoring and antigen presentation Ependymal cells Ciliated cuboidal / columnar epithelium that line ventricles Cerebral Hemispheres have Sulci and Gyri // Cerebellum has Folium (equivalent to sulci in cerebrum) The brain has (in general) Grey Matter outside and White Matter inside Whereas the spinal cord has grey matter inside (anterior horn motor, bigger) and white matter outside [opposite] Grey matter contains neurons, cell processes, synapses and support cells White matter contains myelinated axons and support cells Insula lobe of the brain is normally hidden and is responsible for the experience of pain Brain Meninges: continuous with spinal meninges via foramen magnum Dura Mater Arachnoid Pia Mater Enteric Nervous System: Found in the digestive system from the oesophagus to rectum Neurons found in 2 plexuses in the walls of the gut: Myenteric plexus (between outer layers of smooth muscle) Submucosal plexus (in the submucosa) Blood Supply of the Brain Posterior communicating artery is the most common site of an aneurysm = pain 3rd nerve palsy According to the Motor Homunculus: Legs affected in Ant. Cerebral Artery stroke Arms affected in Middle Cerebral Artery stroke Spinal Cord Spinal cord gives rise to 31 pairs of spinal nerves Cervical enlargement (brachial plexus) ; Lumbar enlargement (lumbosacral plexus) Dorsal / Ventral aspects of each segment → Posterior / Anterior roots → subarachnoid foramen → Intervertebral foramina → Posterior root enlarged by (dorsal) root ganglion → Roots fuse to form mixed spinal N. → Ant & Post Rami Spinal cord terminates as conus medullaris (L1/L2), pia mater continues as filum terminale, which is anchored to the dorsum of the coccyx Spinal meninges continue with brain meninges via foramen magnum ; denticulate ligament (pial, arachnoid tissue) that attaches lateral aspects of the spinal cord to the dura. Subarachnoid space is filled with CSF. No subdural space in spine. Epidural space has fat and venous plexus. Central canal extends the length of the spinal cord opening rostrally into the 4th ventricle. Grey matter inside (anterior / ventral horns bigger) ; white matter outside T1 - L2 of the spinal cord has smaller lateral horns which connect the preganglionic sympathetic neurons. Arterial supply: 3 major longitudinal arteries (1 anterior, 2 posterior) from vertebral arteries Segmental arteries from vertebral, intercostal and lumbar arteries Radicular arteries that travel along dorsal and ventral roots Venous drainage via longitudinal and segmental veins Tracts of the Spinal Cord Dorsal Column / Medial Lemniscus Fine touch and Conscious Proprioception Fibres cross in the medulla Spinothalamic tract Carries pain, temperature and deep pressure Fibres cross when they enter the spinal cord itself Corticospinal tract Fine, precise movements particularly of the distal limb muscles (digits) Tract forms pyramids on the anterior surface of the medulla ‘pyramidal tract’ About 85% of the fibres cross in the caudal medulla at the decussation of the pyramids - crossed fibres form the lateral corticospinal tract while uncrossed fibres form the ventral corticospinal tract (cross segmentally) A CVA of the internal capsule can result in a lack of descending control of the corticospinal tract which results in spastic paralysis, hyperflexion of the upper limbs = decorticate posturing Extrapyramidal system Tectospinal tract Input mostly to cervical segments Though to mediate reflex head and neck movement due to visual stimuli Reticulospinal tract Fibres originate in the reticular formation of the pons and the medulla Fibres from the pons facilitate extensor movements and inhibit flexor movements Fibres from the medulla facilitate flexor movements and inhibit extensor movements Influence voluntary movement Vestibulospinal tract Excitatory input to antigravity extensor muscles Antigravity muscles help keep the body upright - soleus, gluteus maximus, extensors of the back Fibres originate in the vestibular nuclei of pons and medulla (these in turn receive input from vestibular apparatus and cerebellum) Play a major role in those experiencing decerebrate rigidity and paraplegia in extension. Lesions of the brainstem at / below the level of the midbrain can result in a lack of descending cortical control of this tract. This leads to the domination of extensor muscle tone and hence hyperextended spastic paralysis. Clinical consequences of spinal cord anatomy Lateral Hemisection of the cord = Brown Sequard Syndrome Ipsilateral paralysis Ipsilateral loss of fine touch and proprioception Contralateral loss of pain and temperature MENTIMETER DVT ANATOMY Posterior compartment of the leg contains posterior tibial vein (a deep vein) A DVT originating in the posterior tibial vein ➡️ popliteal vein ➡️ femoral vein ➡️ external iliac vein in pelvis ➡️ common iliac vein Pelvis divided from lower limb by inguinal ligament, which connects ASIS to PUBIC TUBERCLE Internal iliac vein drains pelvis structures Iliopsoas (inserts into lesser trochanter of femur) enables hip flexion (active) ; but Sartorius (ASIS to tibia) can also help flexion NERVE SUPPLY TO FOOT AND LEG First web space is Deep peroneal N., also supplies anterior compartment of leg (responsible for dorsiflexion hence lesion will result in dorsiflexion, foot drop and high steppage gait) Deep fibular / peroneal nerve supplies extensor hallucis longus (great toe motor) Superficial fibular nerve supplies dorsiflexion of foot and lateral compartment of the leg: Eversion Posterior compartment of the leg and Sole of foot is supplied sensory by tibial N. L5 posterior nerve root lesion would be more widespread Knee jerk: L2 to L4 : femoral N. (Crosses underneath the inguinal ligament and goes into anterior compartment of thigh: quadriceps femoris) Obturator nerve (L2 - L4) supplies medial thigh sensory interaction while Saphenous N (branch of femoral N.) gives sensory innervation to medial part of leg) Issue on active and passive movement: a structural problem !!! FRACTURES OF THE HAND Fracture of surgical neck of humerus: axillary N. Fracture of mid shaft of humerus: Radial n. ➡️ paresthesia of posterior forearm, extensor compartment thus presenting with wrist drop, dorsum of palm thumb, index, third finger (excluding fingertips) Radial N. travels in radial groove of humerus with profunda brachi artery Fracture of supracondylar part of humerus: Median N. The more proximal an injury is the more forearm compared to only hand signs LAMINECTOMY Pass through ligamentum flavum ANKLE Gastrocnemius, Soleus and Plantaris insert into Achilles’/ calcaneal tendon all cause plantar flexion with Tibialis posterior all supplied by Tibial N. Tibial N. - S1, S2 for ankle jerk reflex - calcaneal tendon reflex Most common ligament to be torn is anterior talo fibular ligament especially with inversion ankle injury SCIATICA N roots are L4 to S3 Exists gluteal region ➡️ Lies in posterior compartment of the thigh Branches into common peroneal N. (injury to neck of fibula anterolateral compartment of leg) And Tibial N (posterior compartment of leg) Decrease sciatic nerve function will cause decreased power of plantar flexion ULNAR N. Anteromedial part of arm motor supply (anteromedial border flattening) Flexor carpi ulnaris and interossei muscles Guyons canal: wrist Cubital tunnel syndrome: elbow THORACIC OUTLET SYNDROME Scalene triangle Subclavian artery Roots of brachial N. Plexus (hence widespread symptoms) KNEE Cysts: popliteal artery cyst would be pulsatile and very deep and central in knee Great saphenous vein located at posteromedial aspect of knee Small saphenous vein LUMBAR CANAL STENOSIS extension makes backache worse so activities like walking down Flexion makes it better so activities like walking uphill or cycling Spinal N. ➡️ dorsal roots ➡️ anterior rami (sensory to rest of the body) and posterior rami (post. Rami supply the back muscles erector spinae and back skin)